The overall aim of the research plan is to develop a model system to study the regulation of phospholipid synthesis in animal tissue. The chosen system of study is the induction by steroid hormones of phospholipid synthesis in the rooster. The proposed research will be carried out to obtain this goal. Initial experiments will be done with whole animals (control and steroid treated) and the radioactive precursors of phosphyatidylcholine and phosphatidylethanolamine, 14C-choline and 14-C ethanolamine. These studies will provide information on the effects of the steroid on the formation of phospholipids in the liver and their transport to the blood plasma; and on the enzymes involved in the pathways leading to the synthesis of these lipids. Subsequent experiments will involve studies with isolated liver cell preparations from roosters. The effects of diethylstilbestrol on phospholipid synthesis can be analyzed more directly with isolated cell preparations and these experiments will be of primary importance in the development of the model system. The data should provide new insight into the hormonal stimulation of phospholipid synthesis and the control of phospholipid synthesis in animal tissues. Furthermore, this model system may be useful for further studies on the assembly and transport of lipoproteins under normal and steroid-induced systems.